CHICAGO (Reuters) – As many as 42 percent of women who are at intermediate or high risk of getting breast cancer decide not to get recommended MRI screening, even if it is offered for free, US researchers said last week.

A quarter of the women in the study who were offered the free screening test decided not to get it because they feel claustrophobic in the tunnel-like scanners. But many also said they declined because of costs involved if the test reveals something that needs to be followed up.

Some said they simply could not spare the time.

"Very early on we were surprised to notice that very few women would accept that invitation, even though it would be no cost to them," said Dr. Wendie Berg, a breast imaging specialist at American Radiology Services in Lutherville, Maryland, and Johns Hopkins University, whose study appears in the journal Radiology.

Her team studied the reasons why high-risk women who are recommended for the more sensitive MRI breast screening test do not get it.

Magnetic resonance imaging, or MRI, can help identify early breast cancer in high-risk women who tend to develop cancer earlier than women at average risk.

For the study, they identified 1,215 women who were at intermediate or high risk for breast cancer and were taking part in larger clinical trial.

All of the women were at increased risk for breast cancer, but even in a group of high risk women, who have a 25 percent greater lifetime risk of breast cancer because of they have known or suspected genetic mutations in the BRCA1 or BRCA2 genes, the willingness to undergo a breast MRI was limited.

"About 20 percent of our patients fall into that category," Berg said.

"We would have expected virtually 100 percent participation in the study."